Medtronic
Summary
Single chamber:
•Single chamber hysteresis
•Sleep Rate
Dual chamber:
•Search AV
•Managed/minimised ventricular pacing – AAI-DDD mode
*note AAI-DDD is effectively working as ADI-DDD mode
Hysteresis
Accessed from parameters; additional features; single chamber hysteresis/rate hysteresis
•Single chamber hysteresis off, 40, 50, 60bpm
•Rate hysteresis off, 30, 40, 50, 60, 70, 80bpm
Sleep rate
The Sleep Function suspends the programmed Lower Rate and replaces it with a Sleep Rate (slower than the Lower Rate) during a specified sleep period.
The slower pacing rate during the sleep period is intended to reduce the paced rhythm during sleep.
Accessed from parameters; additional features; rate therapies
Sleep: on/off
Sleep rate: 30, 35, 40, 45, 50, ...90 ppm (except 65 & 85)
Bed Time: 12:00 AM, 12:15 AM, .....10:00 PM, 10:15 PM, ...11:45 PM
Wake Time: 1:00 AM, 1:15 AM, .....08:00 AM, ..... 11:45 PM
Search AV
Produces 3 scenarios
•If 8 out of 16 sensed beats occur “on time” (between 15 ms and 55 ms) of the scheduled VP there is no modification of the AV delay
•if 8 out of 16 sensed beats occur “early” (more than 55 ms) before the scheduled VP, AV delay is decreased by -8 ms
•If 8 out of 16 sensed beats occur “late” (within 15 ms) before the scheduled VP or 8 of the last 16 events were paced, AV delay is increased by 62 ms
Accessed from parameters; parameters; intrinsic activation and AV intervals
•Search AV: On, off
•Max increase to AV: 10, 20, 30, …170, …250 ms
Minimised ventricular pacing (MVP)
The MVP modes, AAIR<=>DDDR and AAI<=>DDD, provide AAIR or AAI mode pacing while monitoring AV conduction.
For persistent loss of AV conduction, the pacemaker switches to DDDR or DDD mode.
For AT/AF episodes, device switches to DDI
•After switches back to DDD until AV conduction search
If AV conduction resumes, the pacemaker switches back to AAIR or AAI mode.
•The device will drop one beat every 16 hours to check AV conduction
PR Intervals are only restricted by the underlying atrial rate or sensor rate; VS events simply need to occur prior to the next AS or AP.
V. Back-Up Pace
•Scheduled after any A-A interval without V-Sense
•Delivered 80 ms after the scheduled A-Pace (or the inhibited A-Pace)
•Uses programmed V-Amplitude and pulse width
Switch from AAI(R) to Temporary DDD(R) Mode
•Ventricular support if loss of A-V conduction is persistent.
•2 of 4 Most recent A-A Intervals with No Conducted VS Event
AV Conduction Check (1 beat)
•Scheduled every 1, 2, 4, 8 min. . . up to 16 hrs after a transition to DDD(R) has occurred.
•Temporarily uses AAI(R) timing to monitor for a conducted VS during one A-A interval.
•If VS occurs, Conduction Check passes, Mode switches from DDD(R) to AAI(R).
•Scheduled conduction check fails to find conducted VS
•Mode returns to DDD(R)
•Next conduction check scheduled to occur at 2x the previous time interval (1, 2, 4, 8 min. . . 16 hrs)
Updated MVP
(Azure PPMs, Percepta/Serene/Solara CRTP, Cobalt/Crome CRTDs)
•MVP does not wait until the next A event to detect loss of AV conduction
•It learns the pts conduction to best adapt to it (similar to search AV+)
•if Vs is late relative to recent AV conducted events, MVP will pace atrium & then pace ventricle with a PAV of 80ms
•The Ap provides AV synchrony to be maintained & prevents retrograde conducted events
•Reduces the V-V length following AV block or PVCs
Accessed from Mode (AAIR<=>DDDR and AAI<=>DDD)
